Rebaudioside A is a steviol glycoside derived from the Stevia rebaudiana (Bertoni) plant. Rebaudioside A (13-[(2-O-β-D-glucopyranosyl-3-O-β-Dglucopyranosyl-β-D-glucopyranosyl)oxy]kaur-16-en-18-oic acid, β-D-glucopyranosyl ester), and stevioside (13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]kaur-16-en-18-oic acid, β-D-glucopyranosyl ester) are the component glycosides of principal interest for their sweetening property extracted from the Stevia rebaudiana plant. S. rebaudiana and stevioside have been consumed for hundreds of years by humans, in various countries, as sweeteners in foods and beverages. More recently, rebaudioside A is been predominantly used as a non-caloric sweetener in a variety of conventional food products, such as cereals, energy bars, and beverages at levels consistent with the acceptable daily intake (ADI) of 0-4 mg/kg body weight a day based on steviol content.
In current practice, rebaudioside A is first isolated from the leaves of the Stevia plant in a mixture of steviol glycosides (Stevia extract) at a concentration ranging from about 30-60%. Other glycosides most commonly present in the extract include rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, dulcoside A, rubusoside, stevioside and steviolbioside, which are generally present in preparations of steviol glycosides at levels much lower than stevioside or rebaudioside A.
Because these other steviol glycosides carry a bitter after-taste, a whole industry has developed to provide processes to purify rebaudioside A to remove these less desirable glycosides. Predecessors to the present inventors have prepared rebaudioside A compositions having purity levels of more than 96.6% but less than 98.5%, with varying concentrations of the remaining steviol glycosides. However, there remains a need to develop purer rebaudioside A sweetener with better tasting and more readily soluble properties.